The present invention relates to a device for sensing the color of light emitted by a light source or the color of an article, i.e. the color of the light reflected from or transmitted through the article.
For sensing or discriminating colors, photoelectric colorimeters are widely used which comprise a plurality of photoelectric detectors, e.g. photocells, a filter arranged in front of each of the detectors and having the desired spectral transmission characteristics, and an electric circuit for processing the output signal from the detector. The spectral sensitivity curve afforded by the spectral sensitivity of the photoelectric detector itself combined with the spectral transmission characteristics of the filter must be in agreement with the color matching function of the XYZ colorimetric system. However, it is extremely difficult to fulfill this requirement by existing filters in whatever combination, chiefly because the x value of the spectral tristimulus values, namely x, y and z, has two peaks and because the spectral sensitivity of the photoelectric detector itself varies greatly with the wavelength of light. Further since the conventional photoelectric colorimeter has at least three sets of independent photoelectric detectors and filters, the light is invariably incident on a large area. This means that the device is susceptible to the influence of unevenness of light intensity. If the intensity of the light incident on the detectors differs from location to location, the device is unable to sense colors accurately.